Six Creatures that Show Evolution in Action

While the public might continue to debate about the reality of evolution, researchers in labs see real-life evidence for how species change over time. In fact, some are even able to induce evolution to make a species take on new characteristics it never had before.

Which creatures have been caught in the act of evolution? Take a look at these:

Fruit flies. A University of California-Davis study found that some fruit flies facing stiff competition for limited amounts of untainted food would instead eat from a different food source that had been tainted with cadmium. Over just four generations, some of these flies had adapted to be able to tolerate higher levels of cadmium in their food supplies. "The response was much faster than had been predicted,"said graduate student Daniel Bolnick, who conducted the research.

Viruses. Scientists have found they can actually force the harmless adeno-associated virus (AAV) to evolve to make it easier to use in human gene therapy. By exposing mutated forms of the virus to antibodies that are immune to AAV, researchers were able to breed a generation of viruses with fewer of the proteins that set off warning signals in the human immune system. David Schaffer, a chemical engineering professor at the University of California-Berkeley, said the technique could enable scientists to create a type of AAV in just a few months that could introduce helpful genes into humans without setting off immune reactions.

The tuatara. A lizard native to New Zealand, the tuatara is sometimes called a "living dinosaur" or "living fossil." While their outward appearance hasn't changed much in the 200 million-plus years they've been around, their DNA is evolving faster than that of any other vertebrate scientists have yet studied. "Of course we would have expected that the tuatara, which does everything slowly -- they grow slowly, reproduce slowly and have a very slow metabolism -- would have evolved slowly," said David Lambert, an evolutionary biologist at the Allan Wilson Centre for Molecular Ecology and Evolution. "In fact, at the DNA level, they evolve extremely quickly, which supports a hypothesis proposed by the evolutionary biologist Allan Wilson, who suggested that the rate of molecular evolution was uncoupled from the rate of morphological evolution."

E. coli. Escherichia coli, the bacterium best known for causing outbreaks of food poisoning, can evolve a preference for different levels of acidity over the course of 1,000 generations (which doesn't take long for the fast-reproducing organism). "This exciting approach -- experimental evolution -- allows scientists to investigate the fundamental mechanisms of evolution," said James Hicks, editor in chief of the journal Physiological and Biochemical Zoology. "Prior to the advent of contemporary laboratory techniques, inferences about evolution were based on observation. Now, we can study evolutionary change as it is happening, by selecting organisms that change rapidly, such as the fruit fly or E. coli. This advantage allows scientists to investigate how changes occur and how they affect an organism's individual physiology and overall community."

Blue mussels. When threatened by an invasive crab species, mussels can show signs of evolution in as little as 15 years, according to research from the University of New Hampshire. scientists there found that blue mussels can evolve relatively quickly to recognize new species of crabs (which crush mussels' shells to eat the creatures inside) and go into defense mode by thickening their shells. "It's the blending of ecological and evolutionary time," said zoology researcher Aaren Freeman. "It's an important development in the arms race between these crabs and these mollusks."

Tobacco hornworms. Biologists at Duke University have been able to create two different strains of the same species of hornworm over the course of 10 generations. One strain was black, while the other turned green when exposed to warm temperatures early in its development. "Our work is really the first demonstration that genetic accommodation actually can happen," said Frederik Nijhout, a professor of biology at Duke. "In this case, it happens in the laboratory by artificial selection; but as with all such experiments, we assume that this is a microcosm of what is actually going on in nature."

Sources:

UC Davis, Competing Fruit Flies Show Evolution in Action, UC Davis News & Information

UC Berkeley, Scientists Force Viruses to Evolve as Better Delivery Vehicles for Gene Therapy, EurekAlert!

Cell Press, Tuatara, the Fastest Evolving Animal, EurekAlert!

University of Chicago Press Journals, How E. Coli Evolves to Adapt to Changing Acidity, EurekAlert!

University of New Hampshire, Mussels Evolve Quickly to Defend Against Invasive Crabs, UNH Media Relations

Duke University, Researchers Evolve a Complex Genetic Trait in the Laboratory, Office of News and Communications, Duke University